Astronomy
The Cosmic Distance Ladder: Revealing the Universe's Scale
Quick fact
The cosmic distance ladder shows that the observable universe is about 93 billion light-years in diameter, a scale so vast that light from the farthest galaxies has been traveling for over 13 billion years.
Why this is interesting
Have you ever wondered how astronomers know the universe is billions of light-years across? They use a cosmic ladder—not a physical one, but a chain of clever measurement techniques.